Fans having radial flow rotors in axial flow casings



1962 R. 1.. CARLSON 3,069,071

FANS HAVING RADIAL FLOW ROTORS IN AXIAL FLOW CASINGS Filed March a, 1961 2 Sheets-Sheet 1 Dec. 18, 1962 FANS HAVING Filed March 3, 1961 R. L. CARLSON 3,069,071

RADIAL FLOW ROTORS IN AXIAL FLOW CASINGS 2 Sheets-Sheet 2 flitowaey United States Patent ce FANS HAVING RADIAL FLOW ROTORS IN AXIAL This invention relates to fans having centrifugal fan rotors in axial flow casings, and has as objects to reduce the sizes of, to reduce the noises of operation of, and to improve the performances of such fans.

It has previously been proposed as shown by the US. Patents Nos. 928,624 and 1,604,328, to place centrifugal rotors in the axial flow casings of fans, the air discharged radially by the rotors being turned axially by the casings.

This invention provides an outer casing that is cylindrical except at its air outlet, where it is formed as a frustrum of a cone which converges in the direction of air how, and provides a concentric inner easing that is cylindrical and has the same diameter as the fan rotor except at the outlet of the inner casing, where it is formed as a firustrum of a cone which converges in the direction of air flow. The inner casing is closed at its outlet end, and encloses the shaft of the fan rotor which extends through its opposite end, and encloses the bearings of the shaft. In one embodiment of this invention, the inner casing also encloses a pulley on the fan shaft which is connected to a belt which extends through a fairing which extends through the inner and outer casings, to a pulley on the shaft of an electricmotor mounted on the outer casing. The air inlet end of the outer casing is shaped to provide a convergent, axial inlet passage, formed as a frustrum of a cone, to the fan rotor that has a diameter at the rotor, equal to that of the outlet end of the inner casing. This construction provides aligned, annular outlet passages around the rotor and the cylindrical portion of the inner casing, reducing discontinuities of flow and resulting noise and inefliciency.

Fans of this type are often used for moving hot air and other gases, the heat from which might damage the bearings of the fans.

Another object of this invention is to cool the bearings of such fans.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a side view, partially in section, of a fan embodying this invention;

FIG. 2 is a section along the lines 22 of FIG. 1;

FIG. 3 is a section along the lines 33 of FIG. 1, and

FIG. 4 is a plan View looking down on one of the spin removing vanes of the fan.

An outer casing is cylindrical except that it has a diverging outlet wall 11 formed as a frustrum of a cone. A cylindrical outlet duct 12 has its inlet end connected to the outlet end of the wall 11.

The casing 10 has its inlet end portion turned in to form a diverging inlet wall 14 shaped, except at its inner end where it has a short cylindrical portion 15, as a frustrum of a cone. The wall 14 forms a converging, axial, air inlet passage 16. A cylindrical inlet duct 17 extends around the inlet end of the passage 15. The casing 10 is supported on a base 24.

A centrifugal tan rotor 18 has a diverging side plate 19 with its outer end around the wall portion 15. The fan has a conventional hub 20 to which is attached a back plate 21. The usual fan blades 23 are supported between the side plate 19 and the back plate 21. Shaft 25 of the rotor 18 has its outer end within and secured to the hub 20, and has on its inner end a pulley 26. The shaft 25 is supported in bearings 28 attached to hori- 3,059,071 Patented Dec. 18, 1962v zontally extending struts 27, the ends of which are secured to an inner casing 30.

Auxiliary, radially-extending fan blades 32 are secured to the outer side of the back plate 21, and their inner ends are secured to the hub 20.

The inner casing 30 is cylindrical except that it has an inner wall portion 34 shaped as a frustrum of a cone. The casing 30 has a closed outer end wall 35, and has an inner end wall 36 with a central clearance opening 37 around the hub 20. The wall portions 11 and 34 have extending through their upper portions a cylindrical fairing 40 through which extend belts 41 on the pulley 26, and on pulley 43 of electric motor 44 supported on the top of the outer casing 10. The inner casing 30 is supported trom the outer casing 10 by spin removing vanes 45.

The cylindrical portion of the inner casing 30 has the same outer diameter as that of the fan rotor 18. There is an annular passage 46 between the rotor 18 and the outer casing 10, and between the inner casing 30 and the outer casing 10. The spin removing vanes 45 extend across the downstream end of this passage.

There is a diverging outlet passage 50 between the wall portions 34 and 11. This passage diverges so as to more completely fill the duct 12.

In operation, the rotor 18 is rotated through the shaft 25, the pulleys 26 and 43 and the belts 41 of the motor 44, and draws air or other gas to be moved, from the duct 17, and through the inlet passage :16, and discharges the air radially into the annular passage 46 around the rotor 18. The outer casing 10 turns this axially so that it passes through the passage '46, and through diverging discharge passage 50 into the duct 12.

The air entering the passage 46 from the rotor '18 is spinning as a result of the rotation of the rotor, and flows in .a horizontal spiral through the passage 46 without ohstruction or change in general direction until it has its spin removed by the vanes 45 at which time its spin velocity is converted into pressure.

The auxiliary fan blades 32 are rotated with the rotor 18, and draw air from the space around the fan, through the fairing 40, and through the inner casing 30 around the bearings 27, and through the opening 37 in the inner end wall 36 of the casing, and discharge this air into the annular passage 46. Such a fan is frequently used to move air or other gases having very high temperatures which would damage the bearings 28 unless they were cooled hy the relatively cool air drawn over them by the blades 32.

The auxiliary fan system also serves as a dynamic seal tor preventing possibly contaminated gas passing through the main rotor from passing through the inner casing and fairing into the space within which the fan is located.

What is claimed is:

l. A fan comprising a centrifugal rotor having a circular back plate, means forming an axial gas inlet passage into said rotor, an inner casing having a cylindrical portion downstream with respect to gas flow through said fan of said back plate and concentric with said back plate,means including a shaft on the axis of said casing within said casing for rotating said rotor, a bearing in said casing around said shaft, said casing having one end wall adjacent to and parallel to said back plate but spaced therefrom, said wall having a central clearance opening around said shaft, the opposite end wall of said casing being closed, an outer casing having a cylindrical portion around, spaced from and concentric with said cylindrical portion of said inner casing and said rotor, means extending through the downstream portion of said outer easing into said inner casing and providing an air passage from the atmosphere around said outer easing into said inner casing, and auxiliary air moving means on said shaft between said one end wall and said back plate for drawing air through said last mentioned passage into said inner casing, over said bearing and through said clearance opening, and for discharging said air into the space between said inner and outer casings.

2. A fan comprising a centrifugal rotor having a circular back plate, means forming an axial gas inlet passage into said rotor, an inner casing having a cylindrical portion downstream with respect to gas flow through said fan of said back plate and adjacent to and concentric with said back plate, a shaft on the axis of said casing within said casing connected at one end to said rotor, a bearing in said casing around said shaft, a pulley in said casing on the other end of said shaft, said casing having one end Wall adjacent to and parallel to said back plate but spaced therefrom, said wall having a central clearance opening around said shaft, the opposite end wall of said casing being closed, an outer casing having a cylindrical portion around and spaced from and concentric with said inner casing and said rotor, a hollow fairing extending through the downstream end portion of said outer easing into the downstream portion of said inner casing in alignment with said pulley, an electric motor on said outer casing having a pulley aligned with said pulley, a belt around said pulleys and extending through said fairing, and auxiliary fan means on said shaft between said one Wall and said back plate for drawing air through said fairing into said inner casing, over said bearing and through said clearance opening, and for discharging said air into the space between said inner and outer casings.

3. A fan comprising a centrifugal rotor having a circular back plate, means forming an axial gas inlet passage into said rotor, an inner casing having a cylindrical portion downstream with respect to gas flow through said fan of said back plate and concentric with said back plate, means including a shaft on the axis of said casing within said casing for rotating said rotor, a bearing in said cas ing around said shaft, said casing having one end wall adjacent to and parallel to said back plate but spaced therefrom, said wall having a central clearance opening around said shaft, the opposite end wall of said casing being closed, an outer casing having a cylindrical portion around, spaced from and concentric with said cylindrical portion of said inner casing and said rotor, means extending through the downstream portion of said outer easing into said inner casing and providing an air passage from the atmosphere around said outer easing into said inner casing, and auxiliary air moving means on said shaft for drawing air through said last mentioned passage into said inner casing, over said bearing and through said clearance opening into the space between said inner and outer casings.

References Cited in the file of this patent UNITED STATES PATENTS 2,093,748 Becker Sept. 21, 1937 2,187,164 Leathers Jan. 16, 1940 2,245,989 Leathers June 17, 1941 2,309,583 Frantz Jan. 26, 1943 2,335,508 Gustafsson et al Nov. 30, 1943 FOREIGN PATENTS 1,031,705 France Mar. 25, 1953 

